Electrical systems with packaged electrical and electronic components are known and are in use. For example, Motor Control Centers (MCC's) are used for power and data distribution in large and industrial operations. In MCC's, a variety of components, such as switchgear, semiconductor power electronic circuits, programmable logic controllers, motor controllers, and so forth, are housed in large electrical enclosures that may be subdivided into sections or columns, which may be further subdivided into compartments. The MCC includes associated bus bars, interconnections and supporting structures for distribution of electrical power to the various compartments.
Typically, the MCC is connected to a main power line that may feed three-phase AC power to horizontal bus bars of the MCC. The horizontal bus bars, in turn, may feed the three-phase power to vertical bus bars disposed in each of the sections or columns of the MCC. The vertical bus bars, in turn, may feed the three-phase power to various units (which typically include electrical components) that are installed in compartments of a section. The units, in turn, may provide power terminals (conductors), such as copper bus bars, for feeding the three-phase power to a system environment, such as motors, as may be required for various applications.
To connect an MCC to a system environment, a unit having a door or access panel, covering electrical components and sets of load stab conductors may typically be pushed into a compartment of the MCC. A first set of load stab conductors may connect to the three-phase power provided by the MCC, such as via the vertical bus bars. A second set of load stab conductors may connect to electrical connectors leading to screw terminals provided in adjacent wire-ways of the MCC, which may also have a door or access panel. The screw terminals, in turn, may lead to the system environment, such as a motor.
However, in some instances, such arrangements could risk electrical short-circuit and/or shock, such as when making electrical connections with doors or panels removed, leaving screw terminals exposed. It is therefore desirable to minimize the possibility of electrical short-circuit and/or shock where possible.